Air Pump on an 86 Dodge D100

I recently started work on an 86 dodge D100 with a slant six and found all the canister hoses all cut so I went about reattaching them. But when I went by the diagram I found that the previous owner had removed the preheat vacuum lines, removed the cat, and the capped off a vacuum line to what I believe goes to the air pump. I dont see an air pump in my truck and was wondering if I need it or if I should go buy one and install it.